Thomsenolite

Thomsenolith is a rarely occurring mineral from the mineral class of " Fluoride ". It crystallizes in the monoclinic crystal system with the chemical composition NaCa [ AlF6 ] • H2O and developed mostly tabular to prismatic -needle crystals, rarely, radial, or stalactitic massive mineral aggregates and crusty coatings.

Special Features

Reiner Thomsenolith is colorless or microcrystalline form or by lattice defects are white. He may, however, by foreign admixtures such as various iron oxides have a reddish or brownish color.

Etymology and history

Was first found Thomsenolith 1868 in the cryolite deposit at Ivittuut ( Kitaa ) in West Greenland and described by James Dwight Dana, who named the mineral in honor of the Danish chemist Hans Peter Jørgen Julius Thomsen after him.

Classification

In the now outdated nomenclature of minerals by Strunz ( 8th edition ) is one of the Thomsenolith nor to the Department of " hydrous Doppelhalogenide " without further subdivisions, where it forms a separate group together with Pachnolith and Yaroslavit.

Since the 2001 has reorganized and partial redefinition of the classes in the 9th edition of the Strunz'schen Mineral classification is the mineral in the new department to find the " complexes halides " and then in the sub-division of "Island Aluminofluoride ( Neso - Aluminofluoride ) " where it only forms the unnamed group 3.CB.40 together with Pachnolith.

The commonly used in English-speaking classification of minerals according to Dana assigns the Thomsenolith also in the class of halides, but there in the department of " complexes halides - aluminum fluorides with different formulas ," where the mineral forms the unnamed group 11:06:06 the only member.

Modifications and varieties

The chemical compound NaCa [ AlF6 ] • H2O is dimorphic. In addition to the Thomsenolith is also the Pachnolith of the same chemical elements and also crystallizes in the monoclinic crystal system, but in a different space group ( F2 / d)

Education and Locations

Thomsenolith formed secondarily as a weathering product of cryolite or other alkali aluminum fluorides in granitic pegmatites. In addition to cryolite and Pachnolith we find the mineral in paragenesis with Ralstonite, chiolite, Kryolithionit, elpasolite, sellaite and fluorite.

Worldwide, Thomsenolith so far in addition to its type locality, the cryolite deposit at Ivittuut in Greenland, even at nearly 20 localities (as of 2010) are recorded: In the " Demix -Varennes - pit " in Saint- Amable in Québec, Canada; in the slag fields at Thorikos in Greece; on Eldfell in Iceland; at " Werchneje aspen " in Tarbagatai Mountains in eastern Kazakhstan; in Jos ( Plateau ) in Nigeria; at Gjerdingselva ( Gjerdingen ) in Marka ( Norway); in several regions of East Siberia and the Urals in Russia; in " Perzhanskoe Erzfeld " in Ukrainian Oblast Zhytomyr; and in some regions of the United States.

Crystal structure

Thomsenolith crystallizes in the monoclinic space group P21 / c with lattice parameters a = 5.563 Å; b = 5.541 Å; c = 16.115 Å and β = 96.35 ° and four formula units per unit cell.